1. Field of the Invention
The disclosures herein generally relate to a method of making a liquid discharge head, a liquid discharge head, a liquid discharge apparatus having a liquid discharge head, and a manufacturing apparatus of a liquid discharge head. A liquid discharge head may be used for an inkjet recording head in an image recording apparatus or an image forming apparatus such as a printer, a facsimile machine, a copy machine, etc.
2. Description of the Related Art
For years, a piezoelectric actuator has been put to practical use as a part of an inkjet recording head. An inkjet recording head discharges ink from an opening of a nozzle communicating with a pressure chamber by applying pressure to the pressure chamber which is formed partly with a vibrating plate which is deformed by a piezoelectric actuator. One type of piezoelectric actuators practically used is extendable and retractable along the axis direction of the actuator. Another type of piezoelectric actuators practically used utilizes deflection force.
A publicly known method of making a piezoelectric actuator utilizing deflection force is as follows. First, a piezoelectric body layer is formed on a surface of a vibrating plate. Then, the piezoelectric body layer is cut into pieces according to the shapes of pressure chambers by using lithography so that each of the pressure chambers has an independent piezoelectric actuator.
As a piezoelectric body layer, a ferroelectric film such as lead zirconate titanate is used. As a method of forming a ferroelectric film, for example, the “Chemical Solution Deposition method”, also called the “Sol-gel method”, is known. With this method, a ferroelectric film is formed by applying ferroelectric precursor sol, then, executing a heating and crystallization process to crystallize, and repeating these processes for a predetermined count. Japanese Patent No. 3636349, for example, discloses details.
Application of sol may be done with an inkjet applying unit. The applied sol is then crystallized by a heating process to form ferroelectric thin film. With this method, patterning is possible. Japanese Laid-open Patent Publication No. 2011-108996, for example, discloses details. According to this method, the amount of wasted sol may be reduced.
The conventional film-forming method of a ferroelectric film disclosed in Japanese Patent No. 3636349 has a problem in that desired characteristics of a ferroelectric film may not be obtained due to the following reasons. When applying the ferroelectric precursor sol with the inkjet applying unit, variations of nozzles or defective nozzles in an inkjet head may induce misalignment of impact positions of droplets. A small amount of the misalignment may result in less precise patterning, which affects the form of a ferroelectric film and the characteristics.
Incidentally, variations in waiting times between the application of ferroelectric precursor sol and the heating and crystallization process to form ferroelectric film is a cause of variations in forms of the baked paint film.
During a waiting time between the application of sol and the heating and crystallization process, solvent in the application liquid is evaporating. The evaporation changes physical properties of the application liquid. Therefore, the length of a waiting time affects movement of solute during the crystallization, Movement of solute during the crystallization also affects the form of the paint film after the crystallization. When using fast drying application liquid, the form of the paint film is notably affected by the length of a waiting time.
Japanese Laid-open Patent Publication No. 2011-108996 shows an example in which a surface treatment process is executed before applying ferroelectric precursor sol by the inkjet applying unit. Effects of the surface treatment weaken as time passes. Therefore, variations in waiting times between the surface treatment and the application of sol may cause variations in patterning precision.